56 ANALYTICAL MKCHANK'S
6. Prove that the resisting torque due to Motion is ^ivat.r 1W a hollow pivot than for a solid pivot, provided thai tho load and ||H. Inad P,r unit, area are the same in both cases. _ • » • ,
7 Show that the resisting torque duo to trirtion tor a hi>misphi-n«-:il pivot is about 2.35 times as large as tluit fur a flat end pivot.
59. Coefficient of Rolling Friction. -('ons'idcr :i cylinder, Fig. 40, which is in equilibrium on a rough horizontal plum* under the action of a force S-In addition to this force the cylinder is acted upon by its weight and by the reaction of the plane. Applying the conditions of equilibrium we obtain
where F and N are the components of R, the reaction of the plane, while D and d arc, respectively, the distances of the points of application of R and S from the point 0, about which the moments are taken. These equations give* us
If the cylinder is just on the point of motion